The treatment of HIV-1 infection with highly active antiretroviral therapy results in reduction of measurable circulating viral in the plasma, and shifts in the characteristics of circulating lymphocyte subsets. Analysis of lymphoid tissue during the course of antiretroviral therapy is important to compare changes in peripheral versus tissue viral burden and lymphocyte repopulation. In the main study ACTG 387, the addition of cytokines GM-CSF or IL-12 to the antiretroviral regimen may perturb the distribution of tissue macrophages as well. This may be discernible from the histology of lymphoid tissue obtained.